I think the benefits of access to a nation-wide or world-wide market have been enormous and will become even more so in the future. Unfortunately we are realizing that the costs of this transition, if we maintain our current path, are grave. A decentralized approach like OpenBazaar mitigates or eliminates many of the negative side-effects brought on by our current, mega-corporation-dominated access model. With regard to small businesses, an OpenBazaar type system would enable small businesses to trade with the rest of the world (and their local community) on their own terms, without any anti-competitive BS, and without sacrificing profit to platform fees.
The question is: can a distributed system match the value Amazon's service provides to the consumer?
Just because Amazon sucks, does not mean we need to retreat into full-on anarchy over this. Craigslist is also a marketplace and it isn't the behemoth Amazon is.
Also, Amazon provides a lot more than just a market-place. Everything from "inventory tracking to tax collection to credit card processing". These are no trivial features.
You could have started a regular, centralised, open market-place - by the community, for the community type of deal - and get the same benefits. Of course, selling "medicine" would be difficult.. but we all know that is not what this is about, right?
The question is: can a distributed system match the value Amazon's service provides to the consumer?